The slats of blinds can be adjusted by a conventional control device composed of a lifting mechanism and a tilting mechanism. The conventional lifting mechanism 8 of a slat blinds is shown in FIGS. 11 and 12, and generally includes an end cord 81 which has a curved end 811 and a cord wheel 82 on which a lift cord 83 is wrapped. The lift cord 83 includes a loop 831 formed on an end thereof so as to be tied with the curved end 811 of the end cord 81. A first wheel 84 is synchronically rotated with the cord wheel 82 and a coil spring 86 is connected between the first wheel 84 and a second wheel 85. The coil spring 86 is an S-shaped spring and one end of the coil spring 86 forms a coil 861 which provides a torque the same as the weight of the slats 9 so as to position the slats 9 at desired height. When the user pulls the transverse bar at the lower end of the blinds, the cord wheel 82 release or pulls the lift cord 83 and the coil spring 86 keeps the slats 9 at desired position.
The cord wheel 82 and the first wheel 84 are synchronically rotated by using a gear set and the cord wheel 82 is controlled by the coil spring 86. Because the lift cord 83 includes the loop 831 which is tied with the curved end 811 of the end cord 81, so that the lift cord 83 is easily broken after frequent pull and drag. Besides, because the weights of the blinds of different sizes are different so that the cord wheel 82 and the first wheel 84 should be adjustable to meet different sizes of the blinds. Unfortunately, the conventional lifting and tilting mechanisms do not have such function.
The present invention intends to provide a-control device which is cooperated with a gear set to control the slats of the blinds, the gear sizes of the gear set can be adjusted so as to operate slats of different weights.